Ballon catheters having ultraonically driven interface surfaces and methods for their use

ABSTRACT

A catheter comprises a catheter body having an oscillating driver, an interface surface mechanically coupled to the driver, and an inflatable balloon disposed near the interface surface. The balloon may be an angioplasty balloon, in which case the interface surface will deliver ultrasonic or other vibratory energy into a blood vessel as part of an angioplasty or related procedure. Alternatively, the catheter may comprise a pair of axially spaced-apart isolation balloons, in which case the interface surface can deliver ultrasonic or other vibratory energy into a treatment region defined between said balloons. The energy can thus act to mix or enhance penetration of a treatment held between said balloons in performing a vascular treatment procedure.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present application is a continuation of application Ser. No.09/808,725 (Attorney Docket No. 017148-000720), filed on Mar. 14, 2001,which was a continuation application Ser. No. 09/205,061 (AttorneyDocket No. 017148-0007100) filed on Dec. 4, 1998 (now U.S. Pat. No.6,287,272), which was a continuation-in-part of application Ser. No.08/708,589, (Attorney Docket No. 017148-000700), filed on Sep. 5, 1996,now U.S. Pat. No. 5,846,218. The full disclosures of each of theseapplications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to medical devices andmethods. More particularly, the present invention relates to apparatusand methods for performing angioplasty, stent delivery, and relatedprocedures using balloon catheters having ultrasonically oscillatedsurfaces which can impart energy to a blood vessel being treated.

[0004] Despite the growing sophistication of medical technology,vascular (blood vessel) diseases, such as acute myocardial infarction(heart attack) and peripheral arterial thrombosis (blood clots in legarteries), remain a frequent, costly, and very serious problem in healthcare. Current methods of treatment, often expensive, are not alwayseffective. In the U.S. alone, the cost of treatment and support and theloss of productivity due to vascular diseases together exceed $40billion per year.

[0005] The core of the problem is that diseased sites within the bloodvessels narrow and eventually become completely blocked as a result ofthe deposition of fatty materials, cellular debris, calcium, and/orblood clots, thereby blocking the vital flow of blood. Currenttreatments include drugs, interventional devices, and/or bypass surgery.High doses of thrombolytics (clot-dissolving drugs) are frequently usedin an effort to dissolve the blood clots. Even with such aggressivetherapy, thrombolytics fail to restore blood flow in the affected vesselin about 30% of patients. In addition, these drugs can also dissolvebeneficial clots or injure healthy tissue causing potentially fatalbleeding complications.

[0006] While a variety of interventional devices are available,including angioplasty, atherectomy, and laser ablation catheters, theuse of such devices to remove obstructing deposits may leave behind awound that heals by forming a scar. The scar itself may eventuallybecome a serious obstruction in the blood vessel (a process known asrestenosis). Also, diseased blood vessels being treated withinterventional devices sometimes develop vasoconstriction (elasticrecoil), a process by which spasms or abrupt reclosures of the vesseloccur, thereby restricting the flow of blood and necessitating furtherintervention. Approximately 40% of treated patients require additionaltreatment for restenosis resulting from scar formation occurring over arelatively long period, typically 4 to 12 months, while approximately1-in-20 patients require treatment for vasoconstriction, which typicallyoccurs from 4 to 72 hours after the initial treatment.

[0007] The use of ultrasonic energy has been proposed both tomechanically disrupt clot and to enhance the intravascular delivery ofdrugs to dissolve clot and inhibit restenosis. Ultrasonic energy may bedelivered intravascularly using specialized catheters having anultrasonically vibrating surface at or near their distal ends.

[0008] It would be desirable to provide improved devices, systems, andmethods, for treating vascular diseases, particularly stenotic diseaseswhich occlude the coronary and other arteries. In particular, it wouldbe desirable to provide methods and devices for enhancing theperformance of angioplasty procedures, where the ability to introduce anangioplasty catheter through a wholly or partly obstructed blood vessellumen can be improved. Moreover, it would be desirable to providemechanisms as part of an angioplasty catheter, which mechanisms canassist in initial balloon deployment and/or decrease the likelihood ofsubsequent clot formation and restenosis. The devices, systems, andmethods, should further be useful with other procedures which employballoon catheters, including stent deployment and drug delivery, wheredrug delivery can be achieved by deploying a pair of spaced-apartballoons for defining a treatment region therebetween.

[0009] The present invention relates generally to medical devices andmethods. More particularly, the present invention relates to apparatusand methods for performing angioplasty, stent delivery, and relatedprocedures using balloon catheters having ultrasonically oscillatedsurfaces which can impart energy to a blood vessel being treated.

[0010] Despite the growing sophistication of medical technology,vascular (blood vessel) diseases, such as acute myocardial infarction(heart attack) and peripheral arterial thrombosis (blood clots in legarteries), remain a frequent, costly, and very serious problem in healthcare. Current methods of treatment, often expensive, are not alwayseffective. In the U.S. alone, the cost of treatment and support and theloss of productivity due to vascular diseases together exceed $40billion per year.

[0011] The core of the problem is that diseased sites within the bloodvessels narrow and eventually become completely blocked as a result ofthe deposition of fatty materials, cellular debris, calcium, and/orblood clots, thereby blocking the vital flow of blood. Currenttreatments include drugs, interventional devices, and/or bypass surgery.High doses of thrombolytics (clot-dissolving drugs) are frequently usedin an effort to dissolve the blood clots. Even with such aggressivetherapy, thrombolytics fail to restore blood flow in the affected vesselin about 30% of patients. In addition, these drugs can also dissolvebeneficial clots or injure healthy tissue causing potentially fatalbleeding complications.

[0012] While a variety of interventional devices are available,including angioplasty, atherectomy, and laser ablation catheters, theuse of such devices to remove obstructing deposits may leave behind awound that heals by forming a scar. The scar itself may eventuallybecome a serious obstruction in the blood vessel (a process known asrestenosis). Also, diseased blood vessels being treated withinterventional devices sometimes develop vasoconstriction (elasticrecoil), a process by which spasms or abrupt reclosures of the vesseloccur, thereby restricting the flow of blood and necessitating furtherintervention. Approximately 40% of treated patients require additionaltreatment for restenosis resulting from scar formation occurring over arelatively long period, typically 4 to 12 months, while approximately1-in-20 patients require treatment for vasoconstriction, which typicallyoccurs from 4 to 72 hours after the initial treatment.

[0013] The use of ultrasonic energy has been proposed both tomechanically disrupt clot and to enhance the intravascular delivery ofdrugs to dissolve clot and inhibit restenosis. Ultrasonic energy may bedelivered intravascularly using specialized catheters having anultrasonically vibrating surface at or near their distal ends.

[0014] It would be desirable to provide improved devices, systems, andmethods, for treating vascular diseases, particularly stenotic diseaseswhich occlude the coronary and other arteries. In particular, it wouldbe desirable to provide methods and devices for enhancing theperformance of angioplasty procedures, where the ability to introduce anangioplasty catheter through a wholly or partly obstructed blood vessellumen can be improved. Moreover, it would be desirable to providemechanisms as part of an angioplasty catheter, which mechanisms canassist in initial balloon deployment and/or decrease the likelihood ofsubsequent clot formation and restenosis. The devices, systems, andmethods, should further be useful with other procedures which employballoon catheters, including stent deployment and drug delivery, wheredrug delivery can be achieved by deploying a pair of spaced-apartballoons for defining a treatment region therebetween.

[0015] 2. Description of the Background Art

[0016] A catheter system having a pair of spaced-apart balloons with acoiled piezoelectric strip therebetween is described in U.S. Pat. No.5,279,546. Catheters having elongate ultrasonic transmission elementsand inflatable cuffs are described in U.S. Pat. Nos. 5,397,301;5,304,115; and 4,870,953. A tunneling catheter having a radiofrequency,laser, or ultrasonic active distal end disposed within an angioplastycatheter is described in EP 189 329. An atherectomy catheter having anultrasonically enhanced blade disposed adjacent an asymmetricallymounted balloon is described in U.S. Pat. No. 5,085,662. Phonophoresistransducers disposed within porous, inflatable balloons are suggested inU.S. Pat. Nos. 5,286,254 and 5,282,785. Other catheters havingultrasonic elements with the capability of delivering thrombolytic andother liquid agents are described in U.S. Pat. Nos. 5,362,309;5,318,014; 5,315,998; 5,197,946; 5,380,273; 5,344,395; 5,342,292;5,324,255; 5,269,297; 5,267,954; 4,808,153; 4,692,139; and 3,565,062; inWO 90/01300; and in Tachibana (1992) JVIR 3:299-303. A rigid ultrasonicprobe intended for treating vascular plaque and having fluid deliverymeans is described in U.S. Pat. No. 3,433,226. An ultrasonictransmission wire intended for intravascular treatment is described inU.S. Pat. No. 5,163,421 and Rosenschein et al. (1990) JACC 15:711-717.Ultrasonic enhancement of systemic and localized drug delivery isdescribed in U.S. Pat. Nos. 5,267,985; and 4,948,587; in WO 94/05361 andWO 91/19529; in JP 3-63041; and Yumita et al. (1990) Jpn. J. Cancer Res.81:304-308. An electrosurgical angioplasty catheter having ultrasonicenhancement is described in U.S. Pat. No. 4,936,281. An infusion anddrainage catheter having an ultrasonic cleaning mechanism is describedin U.S. Pat. No. 4,698,058. Angioplasty balloon catheters having axialblade atherectomy, ultrasonic imaging, and rotary blade atherectomydevices at their distal ends are described in U.S. Pat. Nos. 5,053,044;5,117,831; and 5,181,920, respectively.

[0017] This application is related to the following commonly assignedpatents and applications: U.S. Pat. Nos. 5,725,494; 5,728,062;5,735,811; 5,931,805; Ser. Nos. 09/033,834; 09/223,230; 09/635,033; and09/653,678. The full disclosures of each of these patents and pendingapplications are incorporated herein by reference.

BRIEF SUMMARY OF THE INVENTION

[0018] According to the present invention, improved devices and systemsare provided which combine both an inflatable balloon and an axiallyoscillated interface surface on a single catheter device. The devicesand systems are useful for a number of intervascular procedures,including (1) angioplasty and related procedures, such as stentdeployment, where ultrasonic energy delivered by the interface surfacecan soften the stenotic material in the blood vessel to facilitatedeployment and initial treatment and can also reduce residual clot inthe treated region in order to lessen the likelihood of restenosis, and(2) drug delivery methods where balloons are used to isolate a treatmentregion and at least one of the balloons is coupled to the interfacesurface so that oscillation of the balloon(s) enhances mixing andpenetration of a treatment medium localized between the balloons.

[0019] The catheters of the present invention will comprise a catheterbody having a proximal end and a distal end. An oscillating driver isdisposed at or near the distal end of the catheter body, and aninterface surface is mechanically coupled to the driver so that thesurface can be axially oscillated relative to the catheter body. Aninflatable balloon is also disposed on the catheter body near theinterface surface, where the balloon can be used for angioplasty, stentdeployment, or the like, and optionally can be combined with a secondballoon to define a drug treatment region therebetween.

[0020] In a first specific embodiment, the interface surface comprises adistal tip which extends laterally over the distal end of the catheterbody. An angioplasty or stent delivery balloon is disposed on thecatheter body proximal to the interface surface. Optionally, theinterface surface can further include a cylindrical portion whichextends over an axial surface of the catheter body. In either case, adistal end of the balloon can be secured directly to the interfacesurface so that the balloon itself is caused to directly oscillate asthe interface surface is oscillated by the driver.

[0021] In use, the catheters having interface surfaces including alaterally disposed distal tip will facilitate penetration of thecatheter through a partly or wholly occluded stenotic region within ablood vessel. The distal tip will be driven, and the catheter advancedthrough the stenotic material, with the ultrasonic energy softening thestenotic material to facilitate advance of the catheter. The balloon,which is proximal to the distal tip, may then be used for either anangioplasty procedure, stent delivery, or both. In either case, theinterface surface on the catheter can thereafter be used to furthertreat the stenotic region with ultrasonic energy to reduce the amount ofclot remaining in order to lessen the likelihood of further clotformation and restenosis.

[0022] In a second specific embodiment, the interface surface isdisposed at least partly within the inflatable balloon on the catheterbody. Preferably, the interface surface and associated oscillatorydriver are both located entirely within the inflatable balloon, so thatthe interface surface can be used to transfer ultrasonic energy directlyinto the inflation medium used to inflate the balloon. Alternatively,the balloon is mounted so that at least one of its forward end and/ordistal end is secured to a cylindrical interface surface. In this way,after balloon inflation, the interface surface will directly oscillateone or both ends of the balloon. The catheters of this type will beparticularly useful for performing enhanced angioplasty procedures,optionally with stent delivery.

[0023] A third exemplary embodiment of the catheter of the presentinvention comprises a pair of spaced-apart inflatable balloons on thecatheter body. A cylindrical interface surface is disposed between theballoons, with at least one of the distal end of the proximal-mostballoon and the proximal end of the distal-most balloon being secured tothe interface member. A fluid delivery lumen is provided within thecatheter so that a treatment medium can be delivered to the regionbetween the balloons when the balloons are expanded in a blood vessel.Mixing and/or penetration of the treatment medium is enhanced byultrasonic oscillation of the cylindrical interface surface when thetreatment medium is present.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 illustrates an exemplary catheter incorporating aninterface surface having a distal tip and an angioplasty balloondisposed proximally of the interface surface, constructed in accordancewith the principles of the present invention.

[0025]FIG. 2 is a detailed view of the distal end of the catheter ofFIG. 1, shown in partial section.

[0026]FIG. 3 is a detailed view of the distal end of a first alternativeembodiment of the catheter of FIG. 1, wherein the interface surfacefurther extends over a cylindrical portion of the catheter body, shownin partial section.

[0027]FIG. 4 is a detailed view of the distal end of a secondalternative embodiment of the catheter of FIG. 1, wherein theangioplasty balloon is attached at its distal end to the interfacesurface.

[0028]FIG. 5 is a detailed view of the distal end of a third alternativeembodiment of the catheter of FIG. 1, wherein the distal end of theangioplasty balloon is attached to the cylindrical portion of theinterface surface of the first alternative embodiment of FIG. 2.

[0029] FIGS. 6-8 illustrate use of the catheter of FIG. 2 forpenetrating a stenotic region within a blood vessel and expanding avascular stent therein.

[0030]FIG. 9 illustrates the distal end of a fourth alternativeembodiment of the catheter of the present invention, wherein acylindrical interface surface is disposed entirely within an angioplastyballoon.

[0031]FIG. 10 illustrates a fifth alternative embodiment of the catheterof the present invention, wherein the angioplasty balloon is attached atboth its proximal and distal ends to a cylindrical interface surface.

[0032]FIG. 11 is a view of the distal end of the catheter of FIG. 9,shown in partial section.

[0033]FIGS. 12 and 13 illustrate use of the catheter of FIG. 9 forexpanding a stent within a stenotic region in a blood vessel.

[0034]FIG. 14 illustrates a sixth alternative embodiment of the catheterof the present invention, wherein the catheter includes a pair ofaxially spaced-apart balloons and wherein the distal end of theproximal-most balloon and the proximal end of the distal-most balloonare each attached to a cylindrical interface surface disposedtherebetween.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0035] The present invention provides apparatus and methods for thetreatment of luminal conditions, particularly for the treatment ofdiseases of the coronary and peripheral vasculature. Specific conditionsinclude coronary and peripheral arterial disease and thrombosis. Theapparatus and methods are useful for primary treatment of such diseases,where the purpose is to ablate, dissolve, or otherwise disrupt the clot,plaque, or other stenotic lesions which are responsible for the disease.For example, catheters constructed according to the principles of thepresent invention can be used to directly engage and transmit vibratory,usually ultrasonic, energy into the stenotic material in order tomechanically disrupt the material to open the associated blood vessellumen. The catheters of the present invention will also include at leastone inflatable balloon in order to perform procedures which combine useof the balloon with the ability to deliver ultrasonic or other vibratoryenergy.

[0036] Usually, the balloons will be angioplasty balloons useful forengaging and dilatating stenotic regions within a blood vessel. In suchcases, the vibratory energy may be used either to enhance initialpenetration of the catheter so that the angioplasty balloon can bepositioned within the stenotic region (e.g. by softening or disruptingthe stenotic material prior to balloon positioning), to soften thestenotic material while the balloon is being expanded with or without astent, and/or to treat the stenotic region within the blood vessel afterthe balloon has been used to perform angioplasty, stent placement, orthe like. In the latter case, the transfer of ultrasonic energy canreduce the presence of residual clot which can serve as nuclei forsubsequent clot formation and restenosis.

[0037] The catheters may also include a pair of spaced-apart balloons,where the balloons define a treatment region therebetween which isuseful to enhance the administration of therapeutic agents, where thetherapeutic agents are primarily responsible for the disruption of thestenotic material and/or lessening of restenosis subsequent toangioplasty. In such cases, the vibratory energy will be relied on toagitate and promote the penetration of the therapeutic agent into thestenotic material. Suitable therapeutic agents include knownthrombolytic and fibrinolytic drugs, such as heparin, tissue plasminogenactivator (tPA), urokinase, streptokinase, and the like.

[0038] The catheters of the present invention will comprise a catheterbody having a proximal end and distal end. The catheter body will havedimensions and physical characteristics selected for the particular use.For vascular applications, the length of the catheter body willtypically be from 50 cm to 200 cm, usually being from 75 cm to 150 cm,and the diameter will be from 1 mm to 5 mm, usually being from 2 mm to 4mm. The diameter of the catheter body may vary over its length, anddifferent portions of the length may be formed from different materials.In the exemplary embodiment, the catheter body will comprise a singleextrusion having at least one lumen therethrough for providing aninflation medium to the balloon. That or another lumen, will usually becapable of receiving a guidewire, and may also be capable of deliveringtherapeutic agents and/or carrying electrical wires for connection fromthe proximal end of the catheter body to the distal end. Alternatively,the catheter body may include separate lumens for balloon inflation,delivering therapeutic agent(s), routing electrical wires for connectionto the ultrasonic transducer, or other purposes.

[0039] The catheter body may be reinforced over all or a portion of itslength. Conventional reinforcement materials include wire braids, wiremeshes, wire coils, helical ribbons, and the like.

[0040] When employed with a guidewire for placement within thevasculature, the catheter body may have an “over-the-wire” design or a“rapid exchange” design. In the former case, the guidewire lumen willextend substantially through the entire length of the catheter body. Inthe latter case, the guidewire lumen will terminate in a proximalguidewire port located relatively near the distal end of the catheterbody, usually within 50 cm, more usually within 30 cm, and often within25 cm or less. Usually, a proximal housing will be secured to theproximal end of the catheter body, where the housing includes aguidewire port, a therapeutic agent infusion port, an electricalconnector, and the like.

[0041] A longitudinally vibrating assembly is secured at or near thedistal end of the catheter body. The assembly will include at least oneinterface surface, usually present on an interface member, which isvibrated at a desired frequency, wherein the interface surface isoriented to transmit vibrations to the fluid environment surrounding thedistal end of the catheter. The vibrating assembly will usually beattached directly to the distal end of the catheter body but also couldbe disposed partially or totally within the distal end of the catheterbody. Usually, the vibrating assembly will have a relatively shortlength, typically being below 2 cm, preferably being below 1 cm, andtypically being in the range from about 0.4 cm to 1.5 cm, more usuallyin the range from about 0.6 cm to 1 cm. The assembly will preferablyhave a low profile (narrow diameter) to facilitate vascular or otherintraluminal introductions, typically having a diameter below 6 mm,usually in the range from 1 mm to 5 mm, more usually in the range from 2mm to 4 mm.

[0042] In a first exemplary embodiment of the present invention, theinterface surface will be forwardly disposed so that the surface mayengage intraluminal obstructions as the catheter is advanced through thebody lumen, such as a blood vessel. In a second exemplary embodiment,the interface member may also or alternatively include an interfacesurface where at least a portion of the surface is disposedcircumferentially about the catheter body. The circumferential portionwill usually be a cylinder, and the interface member and surface willoscillate axially (i.e., back and forth generally in the direction ofthe catheter body). The energy will radiate away from the cylindricalsurface of the interface member in a generally uniform pattern, i.e.,isotropically (radially outward). Such uniform radiation is particularlyadvantageous for softening stenotic material and/or for enhancing thepenetration of therapeutic agents into a length of an intraluminal walladjacent a cylindrical interface surface.

[0043] In the exemplary embodiments, the cylindrical interface surfacewill typically have a length in the range from 4 mm to 30 mm, preferablyfrom 6 mm to 15 mm. The outer diameter of the cylindrical surface willtypically be in the range from 2 mm to 5 mm, more usually from 3 mm to 4mm. The interface member may further include a forwardly disposedlateral surface, typically being formed laterally at the distal end ofthe cylindrical surface. The lateral surface may itself be flat, convex(in the form of a forwardly disposed dome at the distal end of thecylindrical surface), concave, or irregular. The cylindrical surfaceand/or the forwardly disposed lateral surface may also have surfaceirregularities formed therein. For example, a plurality of ridges,protrusions, or the like, may be provided for enhancing the transfer ofoscillatory motion into the fluid adjacent the surface.

[0044] An oscillating driver will be provided on the catheter body foroscillating the interface member in a desired manner. Usually, thedriver will be separate from the interface member. In some cases,however, it may be possible to provide an oscillatory driver which alsodefines the interface surface, particularly for radially oscillatingdrivers as described in copending application Ser. Nos. 08/565,575;08/566,739; and 08/566,740, the full disclosures of which havepreviously been incorporated herein by reference. The drivers willusually be ultrasonic transducers, including tubular piezoelectrictransducers, piezoelectric stack transducers, magnetostrictive drivers,dectostrictive drivers, or the like. Optionally, the drivers may beincorporated in a resonant drive assembly, typically including a springelement attaching the interface member to the catheter body, where theultrasonic driver is a longitudinally oscillating driver disposedbetween the catheter body and the interface member. Longitudinallyoscillating drivers will usually be selected to oscillate with anamplitude in the range from 0.05 μm to 50 μm, often from 0.1 μm to 20μm, preferably from 0.5 μm to 4 μm. The details of such drivers andresonant drive assemblies are set forth in copending application Ser.No. 08/565,575, assigned to the assignee of the present application, thefull disclosure of which is incorporated herein by reference.

[0045] The catheters of the present invention will further compriseexpansible balloon members disposed proximally and/or distally of theinterface surface(s) of the interface member. The expansible members,typically in the form of inflatable non-compliant and/or elastomericballoons, may be utilized to perform angioplasty or engage a luminalwall to isolate a luminal region to be treated. Materials and designsfor incorporating balloons in intravascular and other catheters are wellknown in the art.

[0046] Referring now to FIG. 1, a catheter system 10 comprising acatheter 12 constructed in accordance with the principles of the presentinvention and a power supply 14 is illustrated. The catheter 12 includesa catheter body 16 having a distal end 18 and a proximal end 20, and aproximal housing 22 having a balloon inflation port 24 and a guidewireport 26. Usually, the catheter 12 will have at least a second lumen (notillustrated) for accommodating wires transmitting energy from the powersupply 14 to an ultrasonic transducer, as described hereinafter. Cable30 extends from the proximal end 20 of the catheter body 16 and includesa connector 32 which mates with connector 32 a on cable 33 from thepower supply 14. The power supply 14 will be selected to provide anappropriate current source for driving an ultrasonic transducer, asdescribed in more detail herein below.

[0047] The power supply and transducer will be selected so that theultrasonic driver typically operates in the range from 1 kHz to 300 kHz,preferably from 20 kHz to 80 kHz. For example, the power supply 14 maycomprise a conventional signal generator, such as those commerciallyavailable from suppliers such as Hewlett-Packard, Palo Alto, Calif., andTektronics, Portland, Oreg., and a power amplifier, such as thosecommercially available from suppliers such as ENI, Rochester, N.Y., andKrohn-Hite Corporation, Avon, Mass.

[0048] Referring now to FIGS. 1 and 2, the catheter 12 includes avibratory assembly 40 at its distal end 18. The vibratory assembly 40includes a distal tip 42 connected to a tail mass 44 by a spring member46. Conveniently, the distal tip 42, tail mass 44, and connecting spring46 may be integrally formed, although such integral construction is nota requirement for the present invention. An oscillatory drive assembly50 is disposed between a proximal surface of the distal tip 42 and adistal surface of the tail mass 44, and may comprise a cylindricalpiezoelectric element, such as those described in copending applicationSer. Nos. 08/565,575 and 08/566,739, the full disclosures of which havebeen incorporated herein by reference. Other longitudinal drivers, suchas stacked piezoelectric disks and magnetostrictive drivers (asdescribed in copending application Ser. No. 08/566,740, the fulldisclosure of which has previously been incorporated herein byreference), may also find use. The vibratory assembly 40 will be able tolongitudinally oscillate the distal tip 42 so that a forwardly disposedlateral surface 52 may be longitudinally oscillated, typically with anamplitude in the range from 0.05 μm to 20 μm.

[0049] An angioplasty balloon 60 is disposed on the catheter body 12proximal to the distal tip 42, typically being spaced-apart from the tipby a length in the range from 0 mm to 30 mm, typically from 2 mm to 10mm. The balloon 60 may be inflated through an inflation port 62 which isconnected to inflation port 24 on the proximal housing 22.

[0050] The distal end of an alternative embodiment of the catheter ofFIG. 1 is illustrated in FIG. 3. There, a vibratory assembly 70 at thedistal end 18 (all common elements of the alternative embodiment will begiven the same reference numbers) of the catheter body 12. The vibratoryassembly 70 includes a tail mass 44, and a spring 46, each of which areidentical to the same elements in the catheter of FIGS. 1 and 2. Insteadof the distal tip 42, the catheter of FIG. 3 includes an interfacesurface comprising a cylindrical interface surface which extends over alength of the catheter body from 4 mm to 30 mm, preferably from 6 mm to15 mm. The distal end of the interface surface terminates in a lateralsurface 52 which may have generally the same geometry as that of thecatheter of FIGS. 1 and 2. The oscillatory driver 50 will generally bethe same as that described previously.

[0051] The primary difference between the vibratory assembly 40 andvibratory assembly 70 is in the nature of the interface surface. Theinterface surface defined by distal tip 42 and FIGS. 1 and 2 providesonly a forwardly disposed, lateral interface 52 surface which is usefulfor engaging stenotic material directly in front of the catheter. Whilethe vibratory assembly 70 includes an equivalent forwardly disposedinterface surface, it further includes a circumferentially disposedcylindrical surface which can impart vibratory energy radially outwardlyinto fluid surrounding the catheter tip. The nature and advantages ofsuch cylindrical and other laterally disposed interface surfaces aredescribed in more detail in copending application Ser. No. 08/566,739,the full disclosure of which has previously been incorporated herein byreference.

[0052] The catheters of FIGS. 1-3 each attach the angioplasty balloondirectly to the catheter body. Thus, vibration of the interface surfacesof those catheters is not directly coupled to the balloon itself.Referring now to FIGS. 4 and 5, angioplasty balloons may be partly orwholly connected to the interface surfaces which are vibrated by theoscillatory drivers. For example, as illustrated in FIG. 4, a balloon 80may be attached at its proximal end 82 to the catheter body 12 and atits distal end 84 to the distal tip 42. In this way, the distal end ofthe balloon 80 may be directly vibrated by the distal tip 42 in order toimpart oscillatory energy to the balloon. The balloon may thus bedirectly vibrated and enhance the transfer of oscillatory energy intothe fluid medium surrounding the catheter. Similarly, a balloon 90 mayhave its distal end 94 attached to the cylindrical interface surface 72of the catheter of FIG. 3, as illustrated in FIG. 5.

[0053] Referring now to FIGS. 6-8, the catheter of FIG. 3 may be used toperform angioplasty and optionally deliver a stent ST. Initially, thecatheter is delivered over a guidewire GW until the distal interfacesurface 52 of the catheter engages the stenotic material S within ablood vessel BV. The oscillatory driver of the catheter is then actuatedso that the distal surface 52 is longitudinally oscillated in order tosoften the stenotic material S and enhance penetration of the catheterthrough the stenotic material. In particular, ultrasonic energy may beradiated forwardly in a pattern indicated by wave front lines 74, asshown in FIG. 6.

[0054] After the catheter has penetrated the material in the stenoticregion S, the balloon 60 may be inflated, optionally expanding the stentST, as illustrated in FIG. 7. After the region has been dilatated, andoptionally the stent ST delivered, the catheter may be moved rearwardlyso that the cylindrical surface 72 is aligned with the region that hasbeen treated, as illustrated in FIG. 8. The catheter may again beactuated, and the cylindrical surface 72 will transfer ultrasonic waveenergy into the medium surrounding the distal end of the catheter, asillustrated by the laterally extending transverse wave lines 73 from thesurface. The ultrasonic energy will further reduce any residual clot orother stenotic materials which may be present after the dilatation inorder to reduce the likelihood of restenosis.

[0055] Referring now to FIGS. 9-11, further alternative embodiments ofthe catheter of the present invention will be illustrated. In FIG. 9, acylindrical interface surface 100 is disposed completely withininflatable angioplasty balloon 102. An inflation port 104 is provided onthe catheter body 106, and actuation of the oscillatory driver, asillustrated in FIG. 11, will impart transverse waves into the inflationmedium within the balloon 102. In FIG. 10, a balloon 110 is attached atboth its distal and proximal ends to a cylindrical interface surface112. In this way, when the interface surface 112 is actuated, both endsof the balloon 112 will be longitudinally oscillated together with thesurface.

[0056] Referring now to FIG. 11, a first tubular transducer 120 and asecond tubular transducer 122 are disposed on the proximal and distalsides of a flange 124 which is located in the middle of a tubular holder126. As illustrated, the transducers 120 and 122 are tubularpiezoelectric transducers, but they could also be piezoelectric stacktransducers, magnetostrictive drivers, or the like, as described in moredetail in copending application Ser. Nos. 08/565,575; 08/566,739; and08/566,740, the full disclosures of which have previously beenincorporated herein by reference. In all cases, the transducers 120 and122 will be wired so that they oscillate longitudinally in the samedirection, but 180 out of phase. In this way, the total distance betweenthe proximal end of transducer 120 and the distal end of transducer 122will remain constant, while the ends of each transducer are displacedaxially in a synchronous manner. An interface member 130 having thecylindrical interface surface 100 is attached to the respective ends ofthe first transducer 120 and the second transducer 122. In this way, thetransducers will be driven in a longitudinally oscillating manner at afrequency determined by the characteristics of the transducers and themass of the interface surface.

[0057] Referring now to FIGS. 12 and 13, the catheter of FIGS. 9 and 11may be used to dilatate and optionally deliver a stent to a region ofvascular stenosis S in a blood vessel BV. Initially, the balloon 102carrying the stent ST is positioned within the region of stenosis S, andthereafter the balloon is inflated, as illustrated in FIG. 12. In orderto further inflate the balloon and implant the stent ST, the transducers120 and 122 are activated in order to longitudinally oscillate thecylindrical surface 102. Such oscillation induces transverse waveswithin the inflation medium within the balloon 102 as illustrated inFIG. 13. The energy will be further transferred into the blood vesselwall, softening the stenotic material and enhancing expansion of theballoon 102 and stent ST.

[0058] Referring now to FIG. 14, a catheter 150 having a proximalballoon 152 and a distal balloon 154 is illustrated. The balloons areaxially spaced-apart, and a cylindrical interface surface 156 isdisposed therebetween. The interface surface 156 may be constructedidentically to the transducer assembly of FIG. 11, except that a fluidtransfer port 158 will be provided in order to deliver a treatmentmedium to the volume between the spaced-apart balloons 152 and 154. Inuse, the spaced-apart balloons 152 and 154 will be inflated within ablood vessel BV to define a treatment region R therebetween. A liquidtreatment medium is then introduced into the treatment region R throughthe delivery port 158. After the treatment medium is delivered to thetreatment region, the cylindrical interface surface will belongitudinally oscillated in order to transfer transverse waves into themedium. The distal end of the proximal balloon 152 and proximal end ofthe distal balloon 154 are secured to opposite ends of the cylindricalinterface surface 156. In this way, the inwardly disposed surfaces ofeach balloon are oscillated together with the interface surface 156.Thus, the balloons themselves can further act to impart vibratory energyinto the treatment medium contained within the treatment region R.

[0059] Although the foregoing invention has been described in somedetail by way of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A method for delivering a stent to a bloodvessel, said method comprising: positioning a catheter carrying a stentwithin the blood vessel; inflating a balloon on the catheter within theblood vessel to implant the stent; and transversely oscillating atransducer disposed within the balloon to deliver oscillatory waves intothe blood vessel wall in the region of the stent.